Analysis method for analyzing deformation of casting in die casting process

Abstract

An analysis method for analyzing deformation of a casting in a die casting process includes obtaining a first die frictional stress exerted by a first die on the casting in a mold opening step, and calculating deformation of the casting in the mold opening step using the first die frictional stress. A predetermined frictional coefficient function is selected from a plurality of frictional coefficient functions based on casting conditions and lubrication conditions. A frictional coefficient at each portion of the casting is output by inputting a temperature of a contact surface between the casting and the first die and a contact surface pressure therebetween into the selected predetermined frictional coefficient function. The first die frictional stress acting on each portion of the casting is obtained by multiplying the contact surface pressure and the frictional coefficient.

What is claimed is: 
     
         1 . An analysis method for analyzing deformation of a casting in a die casting process,
 the die casting process including:
 a step of closing a mold by pressing a second die against a first die, and injecting molten metal into cavities of the first die and the second die and solidifying the molten metal to form the casting inside the cavities; and 
 a mold opening step of opening the mold by separating the second die from the first die with the casting held in the second die, 
   the analysis method comprising:
 obtaining a first die frictional stress exerted by the first die on the casting in the mold opening step; and 
 calculating deformation of the casting in the mold opening step using the first die frictional stress wherein 
 a predetermined frictional coefficient function from a plurality of different frictional coefficient functions based on casting conditions and lubrication conditions is selected, and a frictional coefficient at each portion of the casting is output by inputting a temperature of a contact surface between the casting and the first die and a contact surface pressure between the casting and the first die into the predetermined frictional coefficient function, and then the first die frictional stress acting on each portion of the casting is calculated by multiplying the contact surface pressure exerted by the casting on the first die and the frictional coefficient. 
   
     
     
         2 . The analysis method according to  claim 1 , wherein
 in the mold opening step, the frictional coefficient is a static frictional coefficient from a time point at which the mold opening is started until immediately before a time point at which the second die is separated from the first die, and   the frictional coefficient is a dynamic frictional coefficient from the time point at which the second die and the first die are separated from each other until a time point at which the casting is separated from the second die.   
     
     
         3 . The analysis method according to  claim 1 , wherein
 an amount of movement that the casting moves in the mold opening step from a time point at which the mold opening is started until a time point at which the casting is separated from the second die is obtained based on a draft of the first die and amounts of elastic deformation of the first die and the casting, and   the amounts of elastic deformation of the first die and the casting are obtained using moduli of elasticity of the first die and the casting, the moduli of elasticity of the first die varying with a temperature of the first die, the moduli of elasticity of the casting varying with a temperature of the casting.   
     
     
         4 . The analysis method according to  claim 1 , wherein
 the die casting process further includes a mold releasing step of releasing the casting from the second die after the mold opening step, and   the analysis method further comprises obtaining a second die frictional stress exerted by the second die on the casting when an ejector pin is thrust out of the cavity of the second die in the mold releasing step, and calculating deformation of the casting in the mold releasing step using the second die frictional stress.